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Uncertainty-aware circuit optimization
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Source Annual ACM IEEE Design Automation Conference archive
Proceedings of the 39th annual Design Automation Conference table of contents
New Orleans, Louisiana, USA
SESSION: New perspectives in physical design table of contents
Pages: 58 - 63  
Year of Publication: 2002
ISBN ~ ISSN:0738-100X , 1-58113-461-4
Authors
Xiaoliang Bai  UC San Diego, La Jolla, CA
Chandu Visweswariah  IBM T. J. Watson Research Center, Yorktown Heights, NY
Philip N. Strenski  IBM T. J. Watson Research Center, Yorktown Heights, NY
Sponsor
SIGDA: ACM Special Interest Group on Design Automation
Publisher
ACM  New York, NY, USA
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Downloads (6 Weeks): 3,   Downloads (12 Months): 19,   Citation Count: 28
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ABSTRACT

Almost by definition, well-tuned digital circuits have a large number of equally critical paths, which form a so-called "wall" in the slack histogram. However, by the time the design has been through manufacturing, many uncertainties cause these carefully aligned delays to spread out. Inaccuracies in parasitic predictions, clock slew, model-to-hardware correlation, static timing assumptions and manufacturing variations all cause the performance to vary from prediction. Simple statistical principles tell us that the variation of the limiting slack is larger when the height of the wall is greater.Although the wall may be the optimum solution if the static timing predictions were perfect, in the presence of uncertainty in timing and manufacturing, it may no longer be the best choice. The application of formal mathematical optimization in transistor sizing increases the height of the wall, thus exacerbating the problem. There is also a practical matter that schematic restructuring downstream in the design methodology is easier to conceive when there are fewer equally critical paths. This paper describes a method that gives formal mathematical optimizers the incentive to avoid the wall of equally critical paths, while giving up as little as possible in nominal performance. Surprisingly, such a formulation reduces the degeneracy of the optimization problem and can render the optimizer more effective. This "uncertainty-aware" mode has been implemented and applied to several high-performance microprocessor macros. Numerical results are included.


REFERENCES

Note: OCR errors may be found in this Reference List extracted from the full text article. ACM has opted to expose the complete List rather than only correct and linked references.

 
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CITED BY  28

Collaborative Colleagues:
Xiaoliang Bai: colleagues
Chandu Visweswariah: colleagues
Philip N. Strenski: colleagues